Author(s)

Abstract

We experimentally investigate an optical clock based on 171Yb (I = 1/2) atoms confined in an optical lattice. We have evaluated all known frequency shifts to the clock transition, including the density-dependent collision shift, with an uncertainty of 0.19 Hz, or 3.6× 10−16 fractionally, limited principally by uncertainty in the blackbody radiation Stark shift. We have measured the absolute clock transition frequency relative to the NIST-F1 Cs fountain clock and find the frequency to be 518 295 836 590 865.7(0.9) Hz.